The Professor (Lullabies for Sleeping Monsters)
by blueincandescence
Summary: When Dr. Cho brings her students in for a tour of the Avenger's Tower laboratories, Bruce welcomes the opportunity to play professor again — much to the delight of Natasha, who's more than up for a distraction before the next mission.
1. Chapter 1: Study Group

_Notes : I'm primarily active on ao3, and you can find this story at _archiveofourown .org works/4179273 _._

 _This fic assumes an arrangement between Bruce and Natasha and a backstory to justify it, which I've hinted at here and intend to elaborate on in future fics. Their arrangement is canon-compliant if you squint; I can't resist a good secret relationship trope. Oh, and I clearly do not know how to science. Apologizes all around._

 _For extras (images, songs, videos, meta, etc.) related to this fic, visit_ _monsters-blueincandescence .tumblr ._ com _and click the Navigation button for the Lullabies for Sleeping Monsters: The Professor tag._

* * *

 **THE PROFESSOR**

 **a Bruce Banner & Natasha Romanoff fic**

 **from _Lullabies for Sleeping Monsters_ series**

 **by blueincandescence**

— • —

 **1: Study Group**

— • —

The old-fashioned gold and leather watch encircling her wrist ticked off one more minute — twenty-three to go. Natasha sat back with a long-suffering sigh. She raised her bare legs to prop them on the glass of the art deco table with two deliberate thuds. Steve's disapproving brow flicked over out of habit, but his only response was to echo her sigh. It was Stark's table, after all.

And that son of a smug bastard had jetted off to the French Riviera that very morning, lamenting hours of tedious meetings and corporate politics. He was barely out of the conference room before he was on the phone to Pepper making sure she'd packed 'their' favorite bikini.

The upshot was that Natasha, Steve, and Clint had to sift blind through a data pool of potential mad scientists and former business partners so dark and deep it dated back to Prohibition. It was appropriate that the Stark fortune would end up bankrolling the Avengers, in a ponderous, Pushkin sort of way. It had as questionable an origin as any of them. Half a day of diving into its murky waters later, they had the five biggest names in the dubious but dangerous field of mind control research matched up with hundreds of their students.

Points of light arranged into five portraits to hover over the table. Steve leaned over to rest his palms on the glass, his stance braced. "You know, professors never seemed this sinister when I was at college."

Natasha stretched out widely, the sleeves of her slouchy sheer cardigan falling around her elbows. "Art school in the forties? Bet the co-eds wouldn't agree." More innuendo played over her mouth than that comment strictly deserved. Natasha pushed away her preoccupation of the day by turning her smile too innocent. She had a long list of questions for Captain America and once more an opportunity had presented itself. "What were you doing in art school, anyway?"

Steve's attention still didn't leave the abridged dossiers floating under their suspect lineup. "I got a scholarship."

That much was on the record. "Uh-huh."

Steve's face began to de-granite in preparation for the ribbing he knew she was working up to. She liked to let him see it coming. Didn't feel so much like kicking a world-weary Golden Retriever. He did look over when he said, "And I thought I could work for a newspaper or an animation studio. Do my part."

"'Mickey Mouse socks Hitler in the jaw'?" Pushing off with her toes, Natasha swiveled her chair toward the propaganda posters Tony had put up in tribute. "Doesn't have as nice a ring to it."

"Har, har, Romanoff," Steve said, but they both knew she was letting him off light.

What could she say? 'Carter, Margaret Sharon' had come up more than once today as a Stark Sr., SRR-crossover connection. She kept those questions to herself out of respect for the Founder of SHIELD and former First Lady of Espionage. Natasha's soft spots were getting softer at an alarming rate.

"JARVIS," Natasha called, swiveling back to sketch out what she wanted in the space in front of her.

The AI picked up her train of thought and set about making a web with the most likely living candidates to be tapped by HYDRA, willingly or otherwise, to work on alien tech with properties of mind control. Stark had protested like a PTA mom at a book banning when she had originally suggested uploading the Project Insight algorithm into JARVIS's mainframe, but JARVIS had merely characterized its original coding as 'horrid' and integrated the benign form they'd stripped down into his own processing.

"What do you think?" Natasha asked, addressing the room as Clint wandered in to join them. "JARVIS is Stark's most redeeming quality?"

"Slushie machine in the video lounge," Clint countered, setting down his industrial-strength laptop. No one was less impressed with Stark's interface tech than Clint; not even Thor, who'd once been delighted to compare it with a toy he'd had as a child.

"Get your head cleared?" Steve asked. He hadn't said so, but obviously he counted Clint's decision to go work outside on the party deck level a break in productivity.

Clint hadn't said so, but obviously that had been the idea. "For a bit. Dr. Cho's Banner fan club went on break, and a couple of them saw me out there and wanted to talk wind resistance on arrows." He leaned back with his fingers laced on the back of his head, the picture of 'not even considering getting back to work.' "Kids had some pretty good ideas."

Natasha's lip had taken up a quirk at 'Banner fan club,' and it didn't seem to want to go down. She played it off as a smirk in Steve's direction.

There it was, that touch of a frown. "We could really use Dr. Banner's assistance."

"And Stark's and Thor's. Hill's — hell, Fury's." Clint shrugged. "We're what we got."

"Don't forget JARVIS," Natasha said, indicating the changing pattern of lights.

"Happy to be of assistance, Ms. Romanoff."

Of the five professors, the ones affiliated with MKUltra, the Freemasons, Unit 731, and Mossad disintegrated, leaving only the Leviathan angle in play.

"Never trust a Ruski," Clint said, as he did. He grinned when Natasha rolled her eyes. "Pavlovian response. Mind control."

"Dr. Johann Fennoff, also known as Ivanchenko," Steve stated. "Pull up that SSR file again."

Not that it wasn't a kick reading about Peggy Carter in action — not to mention JARVIS's fairly dashing human namesake — but if Steve wanted to go maudlin, he could do it on his own time. Instead, Natasha said, "JARVIS has Fenhoff's current active protégés ready."

"I could Google the SSR file for you," Clint offered, never missing a chance to censure what he'd verbally eviscerated as her 'suicide move' of dumping all of SHIELD's files onto the public domain.

He had very nearly been right, as it turned out. But 'very nearly' was a long way from 'dead and buried' in Natasha's book. She'd had a very large, very angry ace up her sleeve that Clint hadn't considered as a part of her survival strategy. Why would he? Even she'd refused to play it until the last possible hand.

After eight hours of inputting data, the algorithm had narrowed the population of the Earth down to eighteen potential HYDRA recruits to work on the Staff. "Give me six," Steve said, so Natasha further narrowed the candidates to those who had family or debt — standard coercion parameters. They weren't going to get very far with the fanatics, anyway. That got her seven, so she bumped the Russian woman just to spite Clint.

He noticed and approved. "Probably a true believer."

Natasha said, "So we have six people who might be now be HYDRA, might, as we speak, be working on unlocking the Staff's mind control potential on a planet-wide scale."

"Yup, 'might be,'" Clint echoed, in his usual unhelpful way. "If mind control is even what they dummied up a Staff and switched it out for."

Natasha pulled up the mission specs she'd been working off and on again, feeling another long-suffering sigh coming on.

It was stifled by the miracle that was Maria Hill. She'd somehow found time on the floor of the United Nations to plug in all the placeholders Natasha had set, making sure they would have access to blacked out safe houses and contacts too buried to have gotten backlash from the file dump. If anyone could convince the General Assembly it was enough that the Avengers operated in the spirit of the UN Mission, nothing more formal required, it was Maria. Thor was just regal window-dressing.

Steve, who had been silent for a long moment, finally said, "The fact is, we don't have any facts. Your observations on site, Barton, tell us the Staff was likely switched out four months before SHIELD fell. That's half a year's jump they had on us before we even realized alien tech was in play. Now add six more weeks of blind raids and dried up leads. So we start with our best guesses — "

"Or we wait for a bunch of blue-eyed zombies to start scaling the walls to get at us," Clint said. "I'm with you, Cap." He jerked his head toward Natasha. "It's just someone's gotta balance out that one's optimism."

Steve hung his head for half a second, amused in spite of himself, before he pushed off the table to stand upright. "Just tell me neither of you are planning vacations."

"Captain Rogers," JARVIS interjected. "Mr. Stark has instructed me to remind anyone using the word 'vacation' in reference to him that he has gone to the Riviera for a work function."

Natasha watched as the minute hand made the switch to 5:15. Self-imposed boundaries were the most important to stick to. She deserved a break hours ago, and now she had a reason to take one. "Think of it this way, Cap, we all have a role to play."

"Sure," Clint agreed. "Thor's playing ambassador for aliens, monsters, and — " he indicated the three of them " — others under UN suspicion."

"And Stark is keeping us bankrolled." Natasha stood up and slipped her feet into her flats. "Pity he has to do it from afar, but we'll think of him in the blessed silence."

That got a snort. "Okay, okay. You're dismissed. We'll figure out what to do — "

Natasha flicked a wrist, and the specs formed above Steve and Clint's heads. "Fact-finding mission, multiple stops, tag-team, under the radar. We can hardly hope for undercover, but no shield, no arrows. Call it a week and half, if we're efficient, which means one day in Marrakesh, Barton. One."

"Oh, come on, Cap's never been." As an aside, he told Steve, "There's this dive off of Djemaa el-Fna square — all the usual stuff, but I know guys who would sell their mothers for the kefta tagine they have in there. We'll pack it away. You'll thank me."

"Well, I liked the Shawarma," Steve said gamely.

Over them, Natasha said, "I'm going to put Banner to work on supplying us an hallucinogenic convincing enough to shill-by-proxy as mind control. Be ready to leave at twenty-one hundred."

"Do you really think Banner can whip something like that up in a few hours?" Clint all but scoffed.

Well, no, but, "How do you think he got that fan club? Don't keep me waiting."

She left the room to a salute and a "Yes, ma'am."

Unlike SHIELD, the Avengers had a lot less in the way of mind-numbing bureaucracies and hierarchies. Since Maria hadn't cleared the Stark Industries staff for direct Avengers operations, the trade-off was a hell of a lot more legwork, or, ass-work, really. Natasha rolled out her body as she walked. She hoped she never had to understand how the nine-to-fivers did it.

Still, the beauty of micromanaging was that she'd given herself plenty of time before they headed off to maybe slip out of the Tower for some much-needed exercise. In the privacy of the elevator heading up, Natasha indulged a hum of satisfaction to be had. She ruffled the A-line skirt of the patterned mini-dress she'd pulled from the back of her civilian stash, admiring the calculated subtlety of the Lolita effect mirrored in the metallic doors.

Also unlike SHIELD, the Avengers had no mandatory discloses on fraternization to scare off the deeply private and charmingly repressed.

Throughout her SHIELD tenure, she'd let it be widely assumed that the Black Widow was breaking protocol to have cold, punishing sex with any number of colleagues. The rumor mill self-supplied the identities of her victims — Barton, always, sometimes Fury or Hill, and whatever STRIKE asshole wanted to earn his stripes that week. It had been a useful reputation to have in place for the build-up to her debut as a traitor but tedious to keep up later on.

In reality, she'd always kept her personal life profoundly professional — undercover, afterhours, and off the record.

Those three tenets held fast and true for her arrangement with Bruce, except that he was in on the game. And that fact was proving all the difference. Identity crises and near death experiences were a bitch to come back from, but this wasn't the first time Natasha had made the climb. This time around, it wasn't going to be all blood debts and red ledgers. It had taken her actual years to learn how to enjoy her life; no one — not HYDRA, not the KGB — was taking that. Sex was fun again, and not a moment too soon.


	2. Chapter 2: Lecture Notes

— • —

 **2: Lecture Notes**

— • —

It was 5:20 when Natasha stepped out of the elevator, and everything seemed to be right on schedule according to the agenda she'd pocketed yesterday. Stark had insisted Bruce use his lab for the Q & A lecture, so Natasha was able to watch him through the glass as she crossed the atrium to the stairs. He was gesturing back and forth between two rotating visuals, the leather patches on his tweed jacket puckering as he did.

Among the audience of ten students and five professionals in varying degrees of business attire, a hand shot up. A young woman wearing an expensive pantsuit that looked to have been borrowed from her mother stood up to incline her head and ask her question.

The general focus off of him for the moment, Bruce ran a hand over his shorn hair. Natasha could admit to herself that she missed the curls. So did he, it seemed, but he was still attached to his sad little clippers ritual, as if a haircut was one of the many sacrifices he owed polite society.

Twisted, but no part of their arrangement gave her leave to voice that concern. Another of her self-imposed boundaries, and one that Natasha would enforce. Their days of holding up a mirror to each other's most unflattering angles had come to a close. They'd put in the work to be friendly, and friendly was the only way their arrangement could operate.

When Bruce turned his back to maneuver an image, Natasha stepped through the whisper-soft automatic doors. She traded a nod with the head of hospitality, Dara Setiawan, and leaned against the opposite wall, out of Bruce's eye-line. Dr. Helen Cho, standing back and to the left of Bruce, noticed Natasha and gave a polite smile of welcome. This morning had only been their second meeting, but Natasha could see why Stark was putting so much effort into courting her lab into a partnership. Her assessment of Dr. Cho was that she was brilliant and discreet; two things that should go hand in hand that too often did not. Ironic, of course, that Stark put so much stock into the pairing.

At the student's request, Bruce was going over a formula, retracing his steps. Natasha recognized Bruce's symbol for gamma radiation and several others, but he could have been sharing his proposed idea for the destruction of the sun for all she could make out. Several heads were bobbing along in understanding. When they started to fade, Bruce moved back two lines, then two more — "positive regrowth" and "regenerative tissue," he said, the timbre of his voice taking her hand and walking her forward. Suddenly, Natasha was looking at his formula for irradiated medicine instead of a demented scrawl, and the atmosphere of the room was of quiet dawning. He lost her again somewhere around "refracted isotopes," but he carried the students through to the end and received an awed round of applause in return.

Bruce slid his hands in his jacket pockets but did not fold in on himself. Natasha had seen him in his element before — the doctor's bedside manner, the scientist's steady hands — but the professor's ease of authority was something else. Bruce had been teaching long before he'd gotten his doctorate: Desert State, University of Pennsylvania, Harvard, Culver When she'd cased Culver, she'd found that, five years on, his former doctoral students still missed him. The answer to why was proving worth making the time to see.

"Thank you, Soo-jin." Bruce nodded at the young woman, who Natasha could see in profile wasn't offended in the least by Bruce's very American use of her first name. "Great question."

Not helping in his effort to wind down the applause, Dr. Cho stepped forward still clapping. "I think we can all appreciate how monumentally impressive it is that Dr. Banner wrote this formula in the field."

"Well, I drafted it in the field. I wrote it under slightly better conditions," he said, looking around the lab and earning a ripple of laughter. Natasha caught a few hands coming up to stifle giggles. Dr. Cho's Banner fan club, indeed.

She'd wondered why Stark had left the tour to Bruce, since Bruce had made it sound like he'd be parroting the company playbook all day. But he'd been selling himself short, no shock there. It was written on Dr. Cho's face — Stark Industries was the flashy venue; the opportunity to work with Dr. Bruce Banner was the real draw.

He'd come to that realization himself over the course of the day, that much was evident in the magnanimous way he decided they could make time for one more question.

Hands shot up all around, inciting more laughter. Bruce played up the difficulty of the decision, finally pointing at a young man wavering in his confidence. "Always call on the quiet kid in the back," he said, bringing his thumb back to point at himself. The room was his, no doubt about it.

She enjoyed fighting the urge to bring her fingertips to her mouth. Bruce Banner, high on acclaim. The reward centers in her brain were set off just by the possibilities. One in particular made her slide her eyes to the floor as a precaution. Risky, but hadn't she dressed the part this morning with the intention already half-formed? And, really, what was the use of so many self-imposed boundaries if she didn't get to push back against a few of the lesser ones?

Bruce was wrapping up his answer to the question about energy transference in anti-electron collisions that even Natasha could tell was pedantic when she took a step to her left and into his eye-line. The moment he noticed her presence registered as a full-body pause. Natasha, feeling a wicked little grin underneath her mask of curiosity, fixed her gaze.

"Um," he said for the first time, attention on his clasped hands. But he caught up to his train of thought admirably.

She let him finish before she derailed it again. Trepidation met anticipation on a wavelength that passed over the heads of fifteen scientists. Bruce's eyes, pinched under the frames of his glasses, followed the arc of her hand as she raised it in the air. Natasha's sweet smile was every inch the teacher's pet.

— • —

For a reeling moment, Bruce considered not calling on Natasha.

Not because didn't want her here. More like because he did; Bruce had undergone a veritable brain glitch with how pleased he'd been that Natasha must have seen him make everyone laugh, maybe even more than once.

Compound that with legs unusually bare, and, definitely, he considered prying his eyes off her hers and thanking everyone for their time. He had a stack of new journals to pore over courtesy of Dr. Cho. His favorite tea store had gotten in a variety of Oolong he'd never tried. Mundane pleasures, sure. Coma-inducing, according to his critics. But predictable. A stuffed leather chair, for example, would never stare him down with a look so guileless the canary wouldn't know what bit it.

He could just not call on her. He had that prerogative.

Natasha raised her hand a little higher, added a little 'pretty please' to her smile.

Bruce got as far as prying his eyes off of hers. Addressing the floor, he said, "Everyone, I'd like to introduce you to my colleague, Ms. Natasha Romanoff."

When he'd introduced Barton, he'd done it the same way and gotten the same flutter of movement as everyone turned around to whisper and stare. So the realization was slow to wash over him that these whispers were at a lower register, these stares a touch morbid in their curiosity. She'd noticed before he had, of course, and — another unsettling wave; he wasn't used to social anxiety that wasn't firsthand — it showed. Whatever she'd been playing at before had given way to her favorite mask of serenity, this one tinged with more than a hint of omniscient amusement.

Someone muttered something in Korean that included the English "Black Widow" and "Avenger" that caused the backs of several heads to duck and Dr. Cho to look sharply among the students for the source.

Capturing Dr. Cho's attention, Natasha brought her hands in front of her as she dipped into an elegant bow. With great expression, she recited the longer version of the traditional greeting only her help last night had kept Bruce from butchered this morning.

Dr. Cho returned her bow. The rest of the lab went pin-drop silent in trepidation.

Bruce felt his mouth turn up at the corners. Misery did love company. "You had a question for us?"

"It's a little off topic," Natasha said, doing a fair impression of abashed. "I realize this visit is strictly about the Stark Industries move into bio-research." Smiling benevolently at the students still half-turned in their chairs, Natasha said, "But everyone here is so obviously immensely curious." She slid back into cat-and-canary. "About you."

Ah. Bruce folded his arms and looked at the floor. He should have seen this coming.

When Bruce had protested 'Hulk Facts!' as a part of the schedule, Tony had delivered only ten minutes worth of counterarguments about 'giving the kids what they want' and Bruce 'burying his contributions to the field' before he'd crossed it off. Guessing the students would be far too disciplined to stray from the agenda, Tony had come up with a Plan B. And here she was.

Had he really thought Natasha had come just to listen to him lecture?

"Given your long and varied career, I thought it would be nice to end on some words of wisdom from you, Dr. Banner."

"Words of wisdom," he echoed, thrown not to find Tony anywhere in the question. He would have at least called it his 'incredible' career.

There was muted shuffling as the students turned their rapt attention back to him. He glanced at Natasha, who looked for all the world like she was eager to hear his answer. To his left, Dr. Cho smiled in encouragement.

Bruce scratched his head. "I don't know how much wisdom I can claim. It's only been in the later stages of my 'varied' career that I've wised up to much of anything."

The lab assistants in the front row appreciated that one.

The relief allowing him to relax his arms at his side, he continued, "For one, I'd say sell out as soon as possible." He'd gone back to the well for that one, so only a few chuckles. Bruce opened his arms. 'Give the kids what they want,' Tony had said. "Two — and I, really, cannot stress this enough — avoid military contracts."

An oblique mention of the Hulk at best, but the laughter that went through the audience was charged. Bruce couldn't hear Natasha's laugh, but he saw it on her face and promptly had another brain glitch.

From sometime in 1980s Ohio, a nebbish loser, who'd convinced himself there was no difference between 'laughing at' and 'laughing with' when it came to Miss Malinowski, told his future self to get it together. He was going to embarrass himself.

Bruce clasped his hands in front of him. "In all seriousness, we in the sciences — Too often we trample over wisdom in the pursuit of knowledge. A colleague of mine once said to me, right before he had a — " The SHIELD photograph of Samuel Stern's mutated head flashed in front of him. "A disfiguring accident. He said, 'I've always been more curious than cautious.' Curiosity is everything; you lose that and hang up your lab coat, I beg you. But caution is where wisdom comes in. Knowledge offers us a lot of paths between ourselves our objective — saving lives, bettering lives. Wisdom follows the one that allows us to accomplish those objectives along the way."

The applause turned into a standing ovation that lasted too long for his comfort but, still, he couldn't bring himself to truly protest.

A line of bows and handshakes formed in front of him. Natasha stayed where she was. Under her scrutiny, Bruce mostly remembered to hold his forearm with his left hand and refrain from extending his hand to women, although, more than one grabbed his hand of their own accord to give it a vociferous shake. In between, "Thank you for coming," and, "Oh, no, you're too kind, please," he stole glances.

On their way out of the lab, the line of students passed Natasha. They inclined their heads but didn't meet her eyes out of what he knew to be respect, even if it was late in coming. Natasha had a decade on these students, but Bruce was struck by how young, how soft she looked next to them. It took a few glances, but Bruce finally determined it was clothes: the flowing beige cardigan, the pastel pinks of her dress, the flounce that kept the skirt's hemline floating away from her thighs. Light and feminine were the trends of the summer, he'd gleaned from billboards. The style didn't suit Natasha Romanoff in the least, but that had never stopped her from looking —

"Dr. Banner," murmured Dr. Cho, standing to his left. "This is Dr. Huhng."

Whom Bruce had been all but leaning around to leer. He grabbed the man's hand with much too much enthusiasm.

The mental chastising he gave himself got him through the last of the handshakes and his final goodbye with Dr. Cho. Bruce exchanged a wave with Ms. Setiawan that he hoped conveyed his gratitude for all her help today, before she left to escort the group down to the gift shop.

It had been a surprisingly pleasant and a predictably long day. He was exhausted, but when the doors pressed closed he experienced a surge of nervous energy. Finding himself alone with Natasha could mean any number of outcomes, none of which in two and half years' time Bruce had ever found himself prepared for.

— • —


	3. Chapter 3: Class Dismissed

— • —

 **3: Class Dismissed**

— • —

Natasha pushed off from the wall she'd been leaning on with a round of her own applause. Not that Bruce needed any more, but she liked the way he couldn't quite keep his lips turned down. "Here I thought only Cap could pull off impromptu inspirational speeches."

"Thanks. Thanks for the softball question." His eyes were on her feet as she started to close the space between them. She could hear the group in the atrium still filing into the elevators, so she kept a respectable distance. For his part, Bruce took a micro-step back. "Were you taking pity on me, or did you just want to disappoint Tony?"

It never failed to amaze Natasha how easily Bruce could see through her when she had something to hide and, alternatively, just how absurdly obtuse he could be when she didn't.

Off her eyebrow raise, Bruce clarified, "Tony didn't send you to liven up the show by bringing up the Other Guy?"

His obtuseness was even more absurd than usual. "'Send me'?"

Bruce conceded the point with a head duck. He busied himself wiping away the holographics he'd been using as if he were erasing a chalkboard.

She could tell he was about to come up with another perfectly logical reason for her to be there that had nothing at all to do with him, per say, so she interjected, "From where I was standing, it didn't look like the show needed any livening up."

The smile crept back onto his face, in profile.

"Clint was calling them 'The Banner Fan Club,'" she pressed.

That got a chuckle. "No one was more surprised than me," he said, walking toward the far counter. He started putting away lab tools. His back was completely toward her now.

Natasha contained the urge to 'ahem' loudly and gesture to herself. Instead, she confirmed the atrium was empty with a cursory look behind her.

She sauntered up directly behind Bruce, so close that he could turn without brushing up against her but only just barely. In flats, she was eye-level with his collar, the perfect vantage point from which to watch the flush spread up the back of his neck.

Bruce folded his glasses and placed them in the inside pocket of his jacket. "So, you're saying you came all the way up here to watch me lecture?" He managed to turn without brushing her by leaning back against the counter. "No other reason?"

Matching the soft irony of his tone, she replied, "And that's so hard to believe."

"I don't know." That irony increased with his spreading smile. "The idea that I could reach out and touch you right now, and you wouldn't throw me across the room is still pretty unbelievable." His weight was on his hands.

Natasha smiled, too. "So, that's why you don't? No other reason?"

"Oh, cowardice has always been enough of a reason for me."

Bruce Banner, ladies and gentlemen. High on acclaim one minute, spiraling down a hole of self-deprecating humor the very next. But, then, if he ever made things easy for her, Natasha knew herself well enough to acknowledge that might just take the fun out of the thing.

She reached for his tie. "There was picture of you in your old SHIELD file. It was in an article from your UPenn professor days. You'd won a teaching award." Natasha untied the knot over his bobbing Adam's apple. She made a note to nip it later. "You were wearing a jacket like this one. Leaning against a desk, like you're doing now." She slipped the tie from his collar. "No tie. I think you had a beard." She grazed the just-past-five o'clock shadow on his chin. Her fingers found the top three buttons of his blue dress shirt.

"You…" Bruce had to clear his throat. "You have an impressive memory."

"Thank you." Natasha lifted her eyes to watch the deep brown of his irises shrink. "Professor."

He kissed her instantly, only his closed mouth making contact. The apologetic look on his face told her he knew it was clumsy. His eyes darted from her lips to over her shoulder at the still empty atrium. Had Natasha any skin in this game, the flicker of annoyance she felt could have been a problem. As it was, she gave recognition to Bruce's over-sensitivity to being discovered by stepping away.

His tie skimmed the floor as she walked around the corner. Bruce trailed so close behind he treaded on it.

Bruce's lab was adjacent to Tony's and shared the same glass fronts but had, overall, a much less open display. She passed the stairs — up there was even more private, but all in good time — to stand in front of Bruce's refrigerated stores.

She'd lifted her hand to swipe down the list of contents when she felt two hands settle on her hips. She dropped her shoulder and her cardigan sleeve fell with it. Bruce took the hint and pressed his lips into the hollow of her neck. She lifted her arms up and around his head, giving him free range to slide one hand up from her waist, along her ribcage. The other hand skimmed down to past her rising hemline. He stayed like that, his caresses and kisses just past chaste, until a hitch in his breathing told her he was giving into something daring. His hand slid inside her neckline, and Natasha arched her back to feel him against her body.

Bruce let out a puff of agony against her neck, dropping his forehead on her shoulder. "I'm sorry," he said, kneading her breast. "I know we can't…not here."

"Rules are rules," Natasha said, arching further. Another puff, this one even more regretful. Certified genius, and he really hadn't caught on. In fact, he started to detach himself.

With a sigh for the obtuse, Natasha turned to lean against the storeroom door. A shiver passed across her shoulder blades. Bruce rearranged her cardigan to cover her goose-fleshed skin and adjusted her dress back into its previous semi-modest state. Everything about his manner was gentle, but the set lines around his eyes and mouth showed her how forced an exercise of will that was.

"You know what I was thinking when I was watching you?"

Her dress long-since smoothed, Bruce was now just petting her sides. "How odd it is that you enjoy toying with me so much?"

Natasha bit back a grin. "Well, that," she agreed, and he chuckled. "And I was imagining all the hearts you must have broken in all those classrooms."

"God, I hope I spared them that. Teacher crushes are horribly painful — trust me, I would know."

Natasha filed that bit of trivia away for a later date. Today was her turn. "I wouldn't." She let a flush spread across her cheeks and fixed him with that teacher's pet gaze. "Not yet."

The gears shifting in Bruce's brain played out in the way he held his mouth. When it went from slack to hesitant to a touch mischievous, she thought he might have gotten the picture.

"Professor," she said, and his mouth was back on hers, open and insistent. She was starting to think there was something to Pavlovian responses, and that Bruce wouldn't mind a bit if she classically conditioned him this way.

— • —

As soon as he could bring himself to relinquish Natasha's lips and tongue, Bruce was going to swear to her that he'd never had a thing for any of his students. That had never been his fantasy; he had no idea why the sound of her calling him 'Professor' should be pounding in his pulse. The back of her head tapped the glass, and Bruce winced. He brought his arm up to cradle her neck, so he could keep tasting her, deeper and longer.

"Pardon me."

Bruce left his skin, whirling around toward the glass and positioning his body like he could spare Natasha the embarrassment of getting caught.

From behind him, she sighed. "Yes, JARVIS?"

The fact that they were still technically alone registered, finally, and Bruce dropped his head. If only he could spare himself the embarrassment some of the time.

"Terribly sorry for the interruption, Ms. Romanoff, but I have a formal request for Dr. Banner from hospitality."

Bruce raised his eyes to the ceiling. "Yes?"

"Doctor, the group from U-Gin would very much like to include you in their group picture in front of the Tower. They're quite insistent."

There were several reasons to say no. The first was his general avoidance of publicity — Tony, Steve, Thor, and Hill were the face of the Avengers. Despite the inevitable exposure, he, Natasha, and Barton still did their best to stay out of the limelight.

The second was leaning back against his storeroom, dress askew and lips pursed in annoyance. "Tell them Dr. Banner is very sorry he can't join them, but I need him on Avengers business."

"Yes, ma'am. Will that be all?"

"Privacy Protocol, please. If anyone asks, Dr. Banner is readying the serum and needs to be left to his work."

JARVIS replied, "Very good," and his voice faded out as a dark tint over the glass faded in.

"I was going to say no," Bruce assured Natasha, who had her hands on her hips.

She shrugged. "I might as well be the bad guy."

He wanted to ask what that student had said to her. He knew better. "What's the Privacy Protocol?" Bruce was getting the sense that Natasha was changing the rules of their arrangement on him again.

Her eyes tracked him as he came forward. Despite her abruptly uninviting stance, he took a risk and slid his arms through hers. He rubbed her back. He felt distinctly like he owed her an apology, but he couldn't quite put his finger on why. "I had a colleague at Culver, about ten-fifteen years older than me. He was sneaking around with his TA. I'm surprised he never had a heart attack. I almost did just now, and we don't even have an ethics committee. I didn't understand the thrill of it then."

"Well, your midlife crisis was still to come."

Her sharp words brought him up short. She hadn't spoken to him like that since before she'd come back to the Tower. "Natasha," he said. "What is it?" 'What did I do?' was the better question, but he'd already copped to being a coward.

She took her hands from her hips to place on his back. She mirrored his rubbing from before. "You were right before. I had reason for coming up here."

"Am I…" He searched her expression, which was warming back up. "Going to like it?"

Natasha leaned forward to press her lips to his. He felt her form the word, "No," as she said it. She pulled back. "You're really not."

"You actually need me to make a serum?" he guessed. Having seen the disappointment coming did not make it better. Never had. "That wasn't a cover."

"Not exactly." She let go of him to tap on the storeroom doors. "I need the serum we brought back from the Seychelles."

Bruce took a step away from her. He took two more when the thought crossed his mind that she'd been buttering him up. She didn't deserve the jolt of anger he suppressed. Very evenly, he said, "I shouldn't have to tell you — that stuff is dangerous."

"Which is why you destroyed it all, so now there's no more left for the mission. Is that right?" She didn't wait for him to answer, because he'd definitely given himself away. "Pack it up, Doc. Enough to sell."

Suddenly weary, Bruce propped his elbows on the nearest countertop. "Going into business?" he asked, striving for light.

Natasha stepped over to join him, her elbows cattycorner from his. "Steve, Clint, and I are running something on the side. We'll be gone a couple weeks."

So, it was lots of reasons, then. Goodbye was one of them. "New ventures can be time-consuming."

"Well, we're trying to break into a very exclusive market."

The Staff, he realized. Mind control, hallucinogens. Logical plan. "I see. I don't. Like this."

"We'll get every drop we can back," she said, holding eye contact. When he nodded, she looked to her watch. "How long will it take?"

"It's ready. It's still in its casing." They were being honest now, so he admitted, "Most of it."

"Good. You have three hours."

Bruce looked up from his hands. "Did you…" He looked back down.

This was absurd. He was a grown man who had, at one point in his life, asked a brilliant, beautiful woman to marry him. And now he was tongue-tied at the thought of asking this brilliant, beautiful woman if she wanted to engage in an arrangement she herself had proposed. The first time she'd done it, she'd breezed right into his lab, with Tony standing two feet away, and said, 'Come on, Banner, we're going for a walk.' That's all it had taken.

Bruce reached out and touched her hair. "You came to see me lecture, because you wanted to. Tell me I didn't ruin that." The vivid red strands fell against the apples of her cheek when he let them go. "Take a walk with me."

"I don't think we should leave the Tower," she said without inflection.

Privacy Protocol, he thought before doubt could enter in. And he leaned forward to kiss her. He pulled back to make sure he was right.

Natasha smiled that smile, the one he flattered himself was her most genuine. "My, my. Bruce Banner has decided to stop being obtuse." She reached into his jacket and produced his glasses, which she unfolded and centered on the bridge of his nose. "I'll meet you in your office in ten minutes, professor."

With that, she left him standing in his lab, now with a very compelling idea of what the outcome of their next encounter was going to be, and as unprepared as ever. Not that he was in any mood to complain about it.

— • —


	4. Chapter 4: Office Hours

— • —

 **4: Office Hours**

— • —

Though Bruce made a point of taking the stairs one at a time like an adult, his wristwatch interface confirmed that his heart rate was climbing in the direction of horny teenager. Nine minutes.

This was roughly nine times more warning than he'd gotten out of Natasha's arrangement so far. The state of his office was explanation enough for her generosity. It had occurred to Bruce from time to time that he was running out of surface space, but that problem had never seemed quite so disastrous as it did this second.

He started with his stacks of books, sliding them off the carpet and onto the blackwood tiles to rest against geometric shelves more decorative than utilitarian. Off his desk, he moved armfuls of journals, conference papers, and takeout menus onto the other half of the v and the ledge that lined panoramic windows.

The privacy protocol had left the glass transparent, and Bruce couldn't imagine that was an oversight. Calculated risk was a thread between them.

He rolled up the schematics littered behind his desk, propping them against the settee, to make a path to the bathroom. Freshening up without soaking water into the armpits of his shirt or crotch of his pants took some maneuvering, as did zipping up afterward. He didn't want to get too excited, not yet. And he wouldn't.

Bruce might not have been able to control all the disparate neurons Natasha sent firing off in his brain, but the years had made him more than a match for the blood in his veins. He met his eyes in the mirror and conjured the tick of a metronome. His pulse was obedient, leaving Bruce free to examine the way his age caught up to him in the harsh white aesthetic of the office suite. He skimmed his fingertips over the gray that edged his face. Natasha wanted a professor, and she'd certainly cast the part well.

Coming to stand behind his desk, Bruce angled his monitor and his potted cactus further toward the corners. Cleared off, he recognized the spatial advantages of the desktop relative to specific heights. Bruce sat down in his chair, which seemed lower than usual, but that came with an advantage of its own.

Ten minutes had come and gone. Look busy, she'd directed, so he pulled open his Seychelles serum dossier to organize his disjointed notes into a semblance of a mission brief. Bruce hadn't asked why they weren't taking him along. Anything that didn't involve 'Hulk, smash' he could do just as well over comms. He spun his and Natasha's firsthand experiences with the serum's hallucinogenic effects into outside observation, a touch she'd appreciate.

Twenty minutes gone. Bruce kept his eyes off the door, realizing there was a possibility that Steve or Clint could stroll in with a mission-takes-precedent excuse, ready to load up the serum. She'd make it up to him when they got back, were she feeling magnanimous. Mid-sentence, he typed, 'This is the last will and testament of Robert Bruce Banner.' It still filled him with grim amusement, thinking that the Black Widow would be the death of him. A lifetime ago, Betty had told him he never looked harder for a way out than when it was a way out of something good.

A light knock brought him back to the present. He jabbed at the delete button. "Just a minute," he said, and finished his last sentence and the next one, too. Turning to fold his forearms on the desk, he glanced at his watch. "My office hours ended twenty-six minutes ago." The grumpiness that accompanied a class load of intros and no tenure came back to him as if no time had passed.

"I'm so sorry to keep you waiting, Dr. Banner," was Natasha's breathy reply. Her eyes glinted over her abashed smile. She hovered in the doorway, one hand fidgeting with the light green strap that separated and strained her breasts. The digital Hulk face plastered on the flap bulged with the contents of the messenger bag. Next to her pink ballerina flats were two full plastic sacks, the Avengers logo marking them from the gift shop. "I had an unexpected errand."

"What is all this?" Bruce asked, coming around to bring in the sacks, which were full of some Hulk merchandise but mostly _Bannertech_ , the only biography he'd been remotely comfortable authorizing.

"Your homework. JARVIS knows who each one belongs to, so you'll be able to personalize the autographs." Natasha answered his pleased smile with a wolfish one. "Everybody wants a piece of you today."

With low, appreciative noise, Bruce lifted the messenger bag over Natasha's head. The straps had sunk depressions into her milky skin from her collarbone to her swell of cleavage. He brushed his thumb over the line before dipping down to follow the same path with his mouth.

She gasped, "Professor," as if shocked, but petted the back of his neck as he soothed her skin. "I thought you were upset with me." That last part had the air of a cue.

After a moment more in the valley of her breasts, he stepped back to readjust his glasses and his tone. He glanced at his watch again. "I can give you ten minutes, Natasha. Any more you'll have to convince me is worth my time."

"Thank you," she said, voice gone airy again. She flashed him a nervous smile as she slipped past to take a seat, cross-legged, in one of the two chairs in front of his desk.

In her hurry, her skirt puffed up around her thighs. He watched her smooth it, watched the red color her cheeks. He was no stranger to the entertainment value she got from embodying a role, but she'd never asked him to play along when nobody was looking before.

Bruce half-sat on the edge of his desk and peered down at her over his glasses. They slipped and he broke character with a twist of his lips. "What can I do for you?" he asked, sternness gone. He'd never been that kind of a professor, anyway.

"Well, I just wanted to know —" The way her head was tilted, revealing the crookedness of her small, bottom teeth, added infinite sweetness to her hesitant smile. "Well, what you think of me. Uh, as a student."

What he thought was, 'If you'd ever walked into my office with any kind of intent, my academic career would have been over within the month.' What he said was, "Why does it matter what I think?" The tip of his shoe nudged hers.

"Um," she said, and it was gratifying, even as act, to see her self-conscious. Then she rearranged her legs, giving him a glimpse of white cotton and lace and reminding him who was teasing whom. "Well, I find your lectures so fascinating. But I'm worried that I…" Her delicate fingers, fidgeting in her lap, betrayed none of her real strength. "Physics is my area, energy and motion. I don't have much practice with — " She stole a glance that wasn't directed at his face. "With biology or chemistry."

What a line. He couldn't hold back a huff of laughter, self-directed, because it had gotten his attention. When it came to Natasha, his cock lost all discernment. Addressing his cactus, he said, "And so you want what? Private lessons?"

"I-I've gone to all your extra study sessions, and I tried the grad tutors you organized."

Bruce lifted his head. Those were things he'd done at Culver. If her memory was really that good, he wanted to run tests.

"I asked around about you." There was fondness in her voice, the curve of her lips. "Everyone who'd taken your classes said you were one of the best professors they ever had."

The morning of his incident at Culver, he knew from his old SHIELD file, she'd already been there for hours, posing as a PhD candidate. Spying on him. That used to make him angry. Now it made Bruce flustered. Made him want to ask Natasha why it mattered to her that he had been a good professor. If it really did.

She scooted to the edge of her chair, dipped her cleavage toward him. "Please, you're the only one who can help me." Absolute faith shone from her eyes. It resembled the real deal; he'd caught glimpses of faith when he'd done right by her in the middle of life or death. To see it so open — Her hand reached out to rest on his thigh, and his cock twitched beside it. "I'll do anything."

"Natasha," Bruce said past a lump of something souring in his throat, past her role.

She pulled back, the look she fixed him with exasperated. He realized she'd been waiting for him to make a move, while he'd been enmeshed in a fantasy infinitely more troubling than the harmless power play she'd just insinuated.

"I'm sorry," she said, back in character, and stood. "I didn't mean — You must think I'm — "

Bruce took ahold of her wrist, improvising a middle ground between her blithe games and his pathetic crush. "I never told you what I thought of you." He lifted her wrist, and she walked forward, her attention on the shift of their bodies that left her standing between his knees. He told her the truth but only a fraction. "I think you're brilliant."

"Thank you, Professor," she said. Closed her eyes. Parted her lips.

Bruce lifted a hand to span her waist. He pulled her in, cupped her chin. He tested the plumpness of her lips with his thumb. "What do you want, Natasha?"

A crease formed between her eyes as she opened them. "I want you to kiss me." Her tone was half-in character, half-pure Natasha impatience. The tip of her tongue stoked the pad of his thumb.

Despite the strain, he urged, "Why?"

The corners of her mouth tightened for a moment before she made up her mind to humor him. A blush bloomed on her chest, and she let her cardigan pool around her feet. "I'm sure you get this kind of thing all the time. When I watch you lecture…" Her cheek came to rest against his shoulder, and he held her in his arms. "You become so passionate."

The way she murmured the syllables made him press his lips against her hair. He was sure it constituted a forfeit, but she didn't stop.

"Every bit of your intelligence and your curiosity is in your voice, and it just — " Her mouth brushed against his throat. "Runs through me." She nipped his Adam's apple mid-swallow. She leaned flush against him, arms reaching up to curl around his neck. Her expression was pure innocence. "That's why I want you to fuck me, Professor."

Bruce fucked her mouth first. He lifted her onto his lap, invested, mind and body, in the sweet relief of giving Natasha what she wanted.

— • —

Timing the roll of her hips with the thrust of his tongue, Natasha ground down on Bruce like she had no idea about the agony of increasing pressure confined by a zipper. He gripped her thighs, her ass, worked his fingers between their bodies. Natasha rose up enough for Bruce to rub against cotton soaked through with her prolonged anticipation. His moan vibrated the back of her throat.

As the only contemporary expert on the complex neuroses that fueled what turned Dr. Bruce Banner on and when and why and how much, she appreciated his underlying pathology of wanting to be wanted, needing to be made to believe.

That he'd turned cynic on her, pushed her when she'd been nothing but forthcoming — Bruce sucked in a breath that hissed out against her teeth. Well, he could stand a little cruelty before enjoying her kindness.

Her thighs pinned him to the desk, stopping his attempts to move into a more forgiving position. Only when his head jerked back in a full-body flinch did Natasha slide down to stand on her toes. The abrupt loss of contact and rhythm sent her pulsing.

"Can I, Professor?" she asked, not bothering to steady her fingers as she opened the line of his shirt buttons.

"'May I,'" he corrected, his voice as clenched as the grip he took on the edge of the desk. She'd barely touched his belt, just ran a finger over the buckle with a sly smile, before he gritted out, "You may."

Bruce held his breath when she slipped off his belt. But she he was kind, easing down his zipper and cupping him through his briefs to lift him gently from behind unyielding seams. His cock swayed when she let go. He dropped his temple against hers, but the rest of his body stayed tense as he swallowed the urge for release.

Natasha occupied herself by running her fingernails over his chest hair. She brushed a nipple to see his stomach clench. "I feel guilty, Professor," she said, and didn't try to hide a smirk when Bruce huffed a laughed at that absurdity. She murmured, "If we get caught…"

Behind her, the doors to Bruce's office were open. With their temples touching, Natasha could almost feel him sifting through variables: whether or not she'd kept the doors connecting Bruce's lab to Tony's open; how loud they'd have to be for sound to carry to the janitorial staff, who would could come at any time to break down the chairs in Tony's lab; whether they'd guess or say anything if they did hear.

It was an academic exercise; downstairs, Bruce's lab was sealed dark. But, as much as it irked her to realize, the thought of Bruce leaving her to go close his office door set her teeth on edge. Their arrangement was to be strictly between them. She'd made that promise, same as he had. After his jumpy little performance earlier, she had a right to a show of good faith.

Bruce looked away from the door, touching their foreheads.

"You could lose your career," she said, and let that threat stand in for whatever it was that Bruce was really afraid of. The scrutiny of the team, most likely. Tony's barbed comments, Steve's military ethics, what he imagined would be Clint's jealous wrath.

The persistent worry lines around Bruce's eyes crinkled into a devilish squint. "They don't pay me enough to keep my hands off of you." But he let go of her, slid out from under her touch.

She followed him around his desk with only her eyes, wondering what he was up to but enjoying the view. His pants were well tailored enough to stay snug around ass, and his shirt lapels hung open to frame his cock, outlined through his briefs.

Bruce took a seat at his desk. "We should start right away with private lessons. You have a better grasp of chemistry than you gave yourself credit for, Natasha."

Breathily, she answered, "That means a lot coming from you, Professor Banner."

"Let's focus on biology, shall we?" He crooked a finger at her.

One bad line deserved another, but she may have awoken a monster. Natasha climbed onto his desk, all smiles.

— • —


	5. Chapter 5: Private Lessons

— • —

 **5: Private Lessons**

— • —

Watching Natasha crawl across his desk, Bruce could only think, I'm going to hell for this. He thought this because of her uncanny ability to embody a wicked twenty-nine or a virginal nineteen in the space of a blink. He thought this because of all the specific things he wanted to do to her either way. Mostly, he thought this because no one could deserve the sight of such a devastating woman stretching into such an inviting pose. Least of all him. A reckoning was coming for Bruce, and it would no doubt find him still dazed and grateful.

He trailed his hands down Natasha's thighs to take ahold of her ankles. She obliged as he guided her so that her bare feet rested on the armrests of his chair. His hands roved back up her smooth legs, bunching her skirt around her waist. Almost transparent white cotton outlined her clit. He brushed his thumb across it, and she clenched. His cock jumped in sympathy. Her ass was already lifting when he reached for the lacy bands that hugged her hips to slide them off.

Still teasing him with the ingénue, Natasha closed her knees so that he could spread them open again. Bruce leaned back, taking in her glossy folds. He pulled his cock over the waistband of his briefs. He gave his shaft a gentle stroke, her panties wrapped in his fist. "God, you're wet." He managed to grit out, "Feel how wet you are."

Natasha summoned embarrassment, her hesitant hand coming to rest against her thigh. "I've been thinking about you, professor," she admitted. One finger skimmed between her folds.

He stroked with her. His skin was hot under his hand, under her stare. "When?"

"All day." She slipped a finger inside herself, making small circles. "Since last night."

Bruce had to let go of his cock. "Tell me."

"First you were a mission. They sent me to Harvard to turn you into an asset." Christ, she could have done it. He would have learned Russian for her. "Then I wondered, what if I were just one of your students?" She trailed off, letting it be his turn to wonder.

He pictured Natasha in bed, constructing him into a fantasy. He pictured her at Harvard, on scholarship. In any life she would have been brilliant. And cutthroat competitive, too, though no one would have known it. Natasha Romanova, front row, offering half a dozen insights per class. Eyes on him.

He pictured Natasha as she was yesterday evening, sitting in this very chair. There had been no heat in her eyes when she'd corrected his vowel harmony. He had paced between her and Tony, who'd been sprawled on the black leather settee. While Bruce had been caught up in memorizing Korean greetings and Stark Industries talking points, Natasha had been planning —

Bruce bit back a groan, gripped the armrests. "You planned this last night?" Unbelievable, were it not for the fact that he was watching her masturbate on his desk.

"I didn't decide until I saw you lecture." She brought back her cat-and-canary grin. "You were too sexy to resist."

He let the urge to surge up, bury himself in her slick heat fill him before he closed his eyes and swallowed it hard. When the shudder passed, he placed her panties and his glasses on the desk. Bruce took Natasha's hand and brought it to his mouth, then leaned forward into the cradle of her hips. The relief in her moan coaxed his tongue toward her clit. Bruce worked one finger, then a second into her opening.

Natasha lay back on his desk, her feet pushing against the edge to urge him deeper. He buried his face in her pussy, inhaling the scent and lapping the taste that would preoccupy him long after she had shaken his hand and moved on. He tongued around his fingers, stroked upward to roll against her clit and down again. The movement of her hips and the cadence of her moans told him exactly when she was finished with teasing. All day, she'd said. She'd been waiting all day for him to make her come.

The sudden, intense pressure of his mouth on her clit made Natasha cry out. She was already beginning to spasm around his fingers when he curled them against her spot and set a rhythm that he matched with his tongue.

Her feet left the desk and found his back. Any semblance of the coy undergraduate vanished when she gripped the back of his neck and rode his face. "Bruce," she rasped, a warning and a plea and, in Natasha's throaty voice, the most arousing sound imaginable.

It was all he could do not to take hold of his aching cock and come with her.

— • —

The muscles in Natasha's abdomen, her thighs, her pussy contracted and erupted into pulses. Her walls grasped at Bruce's fingers as he pulled them from her opening. His capable hands eased the spasms that trembled her legs. Only Natasha wasn't ready to be gentled. She was ready to be filled.

Undraping her legs from his shoulders, she sat up against the drugging pleasure Bruce had given her. She must have looked as wanton as she felt, if the wicked pride glinting in his eyes was any indication. They fell to her chest, where her dress had folded over and one nipple peeked over strapless bra.

"That doesn't look comfortable," he murmured, reaching around undo the clasp. His face, so close to hers, fairly glistened. She captured his mouth to taste herself on his lips, his tongue. Natasha allowed him to break the kiss just long enough for him to raise her dress over her head. Using either side of his shirt as leverage, she pulled him back to her. His chest hair prickled against her too-sensitive nipples.

Pressing even closer, she tugged off his shirt. Bruce took the hint to step out of his shoes and pants. As much as she liked to watch him undress, she made him do it with their mouths fastened together. She wanted him now, while her nerves still buzzed with her orgasm.

She relinquished him again so he could crouch under his desk to retrieve a condom from his satchel. Sex between them would be safe; her Intrauterine Vaginal Liner protected her from excess gamma poisoning as well as it did viruses. His aversion to his own fluids had more to do with the mental than the physical, as far as she could tell, but she wouldn't argue the point. Natasha had her boundaries. Bruce had his.

As he opened the wrapper, Natasha saw the effort, the tremor. Bruce's intense control was all the more impressive on the verge of slipping. He rolled the condom onto his erection, which swayed, heavy and thick, when he came to stand between her knees.

His furrow of concentration made him look so serious, she couldn't resist teasing him. "May I?" she asked, hand hovering.

"You're a quick stu — " He cut himself off with a groan the moment her fingers gripped his shaft.

Drawing her knees up and out, she guided him to her entrance. Both of them sensitive, he penetrated her with care. The sweet ache of it was mirrored in each other's strained expressions, the grip they had on each other's backs. When he was seated in her, he paused to rest his forehead against hers. His fingers threaded through her hair, and he moved to press his lips between her brows.

Shock jolted through her. Intimacy was a side effect of endorphins; she couldn't hold it against him. "Tease," she complained and shoved her tongue in his mouth.

When his hips began to move, Natasha leaned back on her elbows. He rocked against her in measured strokes. His eyes roved over her body, his hands sought out her softest parts. On his face, she watched his need to let go build, but he held it at bay. Not for her sake, she hoped.

Natasha sat up, and the movement caused Bruce to lose his rhythm and slip out of her. She slid down from the desk. He made just enough space for her to stand with his cock against her belly. She stroked his chest, slick with pent-up exertion. "Professor, may I ask a favor?"

His teeth found his bottom lip, and he gave a shaky nod.

In her sweetest voice, she said, "Bend me over your desk?" She almost demanded a second orgasm, only his cock was pulsing. She dipped into a lower register. "And come inside me."

Bruce spun her around. She was surprised to see him place his folded jacket over the hard edge of his desk before he compelled her onto her elbows. He pushed inside her. Her thighs bounced against the desk, cushioned by the thick fabric. She could have taken the bruising — a part of her might have preferred it. But Bruce, having been considerate, could now be selfish, and that was a turn-on all its own.

With each thrust, Bruce set a faster pace. He gripped her ass for leverage, then her waist as she arched her back. Her pussy clenched and opened around his cock. Her clit was throbbing for attention. Natasha moaned, at once full and aching. She could come again, she just needed —

Natasha lifted one knee onto the desk, and they both cried out when Bruce's cock angled deeper. Shifting her weight to one elbow, she worked her other arm under herself to reach her clit. Her second orgasm was lightning quick. She threw back her head and gasped at the pain-pleasure of Bruce's unfaltering thrusts.

When he came, he did so with a shudder that wracked his body. He pulled his sated cock from inside her, and she sighed at the loss. His arms, on either side of her, shook as they took part of his weight from his trembling legs.

Natasha angled out flat on the desk, and he took the invitation to rest on top of her. The hot weight of his body constricted her breathing and mashed her hip bones but was otherwise pleasant.

Her eyes drifted shut. "Well done, professor. I learned so much."

Bruce's chuckle vibrated along her spine. "Make an appointment anytime."

So, he wanted more forewarning. He probably didn't realize what he'd said, but hint taken. Next time, she thought. Not every time, though. Catching him off-guard was too much fun for that.

"I'm squishing you."

Natasha made a noncommittal noise.

A couple deep breaths later, Bruce was composed enough to stand up from the desk. Natasha, by contrast, was still mostly rubber. That fact should have stung her pride, probably, but she was too smug to care. Not all of her plans came together so nicely. A few minutes later, Bruce returned to lift her into a bridal carry. She hummed in approval.

The settee was far more comfortable than the desk, and Bruce far more comfortable still. Arranged half on his lap, she cracked a lid. He looked almost as smug as she must and just as content. Bruce Banner, ladies and gentleman. High on acclaim.

Her eyes drifted shut again, but her curiosity was awake. Natasha had a specific question she needed to work up to. She started with, "What do you think got your Culver colleague in the end — heart attack or the TA?"

"The TA. Last I heard, they were married with a second batch of kids."

"That almost passes for wholesome." She let the disapproval in her voice speak for itself.

"If you want torrid, I had another colleague at Harvard. We started out as running buddies, then we were drinking buddies." Bruce's leg began to jiggle. "Going back to Harvard wasn't my finest hour. This guy, he was in the English department, but we were in the same boat. Harvard protégées turned disappointments."

"Harvard makes pity hires all the time, I'm sure." Were a copy of _Bannertech_ in reach, she would have been tempted to smack him over the head with it.

He shrugged. "We were Nobel-tracked alums with spotty reputations." Which Natasha took to mean self-destructive tendencies. No one could have stopped the momentum of Bruce's career besides Bruce.

"You said torrid, not sad-sack."

Bruce tweaked her nipple. Natasha couldn't even react except to open her eyes and glare — he'd actually tweaked her nipple. Bruce, grinning sheepishly down at her, already had his hands clamped over his own.

"Ow," she said.

He leaned down to kiss it better, and she let him. Natasha grimaced. The endorphins were getting her, too.

She sat up straight, pulling her feet under her. One arm she draped behind Bruce's head and the other she rested casually on this thigh. He'd washed up when he'd flushed the condom. Her own thighs were still slick. "So, your fellow disappointment, I take it he told you all the sordid particulars of his private lessons? I bet they worshipped him."

Bruce held his crossed arms at the elbows. "It wasn't mutual."

With that, he'd answered her question. "You never had a protégé."

"What? Also, don't act like that obscure detail just came to you." He pulled back from her, expression riding the line between flattered and offended. "You re-read my file. Before or after you got yourself off?"

She traced his earlobe. "Before."

Languid brown eyes sparked with interest. Hers went to his cock, flaccid but not contracted. Bruce could be made to forget he was a man of a certain age, to remember he was a man with an excess of energy to burn off.

"Why?"

That word again. "I wondered if you'd ever slept with a student." She traced the veins of his shaft now. "You would have, but you never found the right one."

"I would have slept with my protégé. Really." Underneath his skepticism, Bruce had clearly decided to be offended.

Natasha sighed. "I offered you a very common fantasy: innocent schoolgirl temptress, willing to do absolutely anything to pass. And you made it into this mutual…" It was in poor taste to evoke the L-word, but there was no other way to describe it. "Love affair, almost. And that turned you on more." She palmed his hardening cock and let him catch up to her conclusion.

He looked away from her face, away from her hand. "Yes, common to porn," he said, sidestepping the point entirely.

"You're not a prude, Bruce." It was absurd, her of all people having to remind him of that.

"No, I'm a pervert." The smile he directed at his erection was close-lipped. Gentle, unassuming Bruce was a prickly son of a bitch when he wanted to be.

She leaned down to kiss the head of his shaft better and was off the settee before he could react. Her step had an extra bounce to it, for his benefit.

Natasha could tell him exactly what he was — an egomaniac with an inferiority complex. There wouldn't be any point, though. Bruce probably told himself that in the mirror every morning, his twisted version of a pep talk. And, anyway, there was so much more to him than that.

From his satchel, she produced another condom, which she placed between her teeth so she could rip it open as she approached the settee.

"If you're a pervert, Professor Banner, what does that make me?" She leaned over to put the condom on him. One of his hands steadied her at her waist, the other palmed a swaying breast.

"The perfect woman?"

"Good answer." She swung a leg over, and he helped her into position. "B-plus."

His eyebrows lifted, and he flashed her a little boy smile. "A harsh grader. I like it."

Natasha rubbed her slit against his thick head before angling down halfway. Bruce voiced appreciation for the both of them.

She set a steady pace, directed the exchange of sighs and moans. She nibbled and sucked, marking him just below where his collar would fall. His hands never stayed still, gripping every part of her he could.

When Bruce cradled her face, she could see from the hazy sheen over his eyes that he was ready to come. He'd called her harsh, but she was fair if the mood struck. She deepened her strokes for him. He brought their lips together.

Between kisses, he murmured, "You're the fantasy." He clenched. "Natasha — "

She milked him through his orgasm, satisfied with the minor pulses it set off for her. The glow spreading through her had everything to do with endorphins. Nothing to do with the second kiss he pressed to her forehead.

"I'm the fantasy?" She buried her face against his chest and groaned. "D-minus line."

Bruce thumbed her cheek. "Now who's being obtuse?"

Her muscles stayed relaxed, but inwardly she squirmed. 'A friendly arrangement' was an abstract concept with variable meanings. He was pushing one of their boundaries, but not crossing it. That was a rationalization, Natasha knew. For all his obtuse, prickly, overly intimate faults, Bruce just wasn't something she was ready to give up yet.

He was massaging her neck now, and Natasha burrowed closer to give him better access. If Bruce wanted to teach her how to enjoy being pampered after sex, well. She could stand to learn a little more about that.

— • —


	6. Chapter 6: Teacher's Lounge

— • —

 **6: Teacher's Lounge**

— • —

Bruce pushed back from his desk with a sigh. Pen capped, he tossed it to rest in the seam of the _Bannertech_ inside cover he'd been trying to personalize and scrubbed his eyes. The image of Natasha posing on his desk was still there when he opened them, clear as a holographic image.

It would probably be days before he could get any meaningful work done in his office without distraction. All part of the fun, he supposed. Standing, he made an attempt at a frustrated noise, only it came out more of a laugh.

He wandered over to the aquarium lighting up the center of the floor to ceiling bookshelf. He watched the five green pufferfish of varying types swim across his amused reflection. Tony didn't know how to give a gift without a wink in his eye. Polypheme and Whopper floated to the top of the tank, anticipating a third absent-minded feeding.

The fish were fed. His office had never been tidier. Actual work was impossible. Natasha had left the building a half hour ago. He should leave.

Bruce had stayed on the settee when Natasha had peeled herself off the leather and him. She'd perched, naked, in his chair and, with a few keystrokes, bypassed his security. She'd scrolled through the dossier, nodding here, editing there. She'd put on her bra and dress. Her panties she'd hung from his monitor. Modest lace and cotton — nobody would have guessed they were hers. She'd gone around the desk to don her cardigan, complete her costume. Both feet on the other side of doorway, Natasha had said, like she always did, "See you when I see you, Doc." Bruce had raised an arm in farewell. He'd said plenty already.

Bruce had gotten dressed but stayed in his office when she'd returned to his lab a while later, duffle bag, Clint, and Steve in tow. He'd listened to the three of them call dibs on who would drive to the airfield, who'd take the first shift of the unchartered flight. He'd flipped through the mission specs as they'd raided his stores. Six countries in ten days, real spy stuff, complete with the tedium. He'd pictured Natasha in a dusty room in Marrakesh, her bare feet propped next to a scanner, a bowl of pistachios in her lap that she alternated between eating and flinging, depending on how bad the jokes got. Bruce had never wanted to go on a mission before.

That was an issue. Running his mouth was another. Natasha's arrangement. Tony's fish and Tony's office. Bruce found solace in pleasures of someone else's design, found it easier that way to stop himself wanting more than he could take. Natasha had a way of making him forget that sometimes, but at least he could count on her to put him in his place.

Bruce left his borrowed office and rode the elevator to another indulgence, this one planned. Unlike most other floors in the Tower, the windows of the study had been done up to look like actual windows, complete with curtains. An exact replica of the library wing of the New York City mansion Tony had grown up in, Pepper had informed Bruce the first time they'd bumped into each other here.

On the end table next to his habitual stuffed leather chair, a mug, a self-heating kettle, and a stack of journals were waiting for him, just as Dara had offered. Along with them was a note: 'Dear Dr. Banner, You may tell Tony Stark he can stop sending me robots. I was suitably impressed, by your contributions most of all. Consider me a partner. Warm regards, Helen Cho.'

Bruce let himself relax into the chair muscle by muscle and poured the tea. The first sip was as delicious as the clerk had promised. He cracked the page of the first journal, excited to see the issue was about the latest in East Asian research on cellular recreation.

Overall, he was inclined to call this a good day.

He was one mug of tea and one article down when the speakers opened and Marvin Gaye's "Let's Get it On" started blaring, followed by Pepper's trilling laughter and some kind of insinuation from Tony. Bruce froze. There was a bearskin rug about three inches from his feet.

"Tony — JARVIS, stop the music."

"Add a record scratch."

Tony and Pepper both laughed when JARVIS complied.

"Don't worry, Bruce." Pepper's voice carried from around a bookcase. "We know you're here."

Oh, thank God.

The pair appeared fully clothed, one arm wrapped tight around each other. Tony carried a bottle of champagne and Pepper three glasses. She swayed, but Tony kept her upright.

"Too much sun," Tony explained, bringing her over to the adjacent sofa.

"Too many cocktails," Pepper added, smile luminous. "I made Tony go to all the meetings today. Hours of them. Alone." She laid her head down on Tony's shoulder and turned her grin on Bruce. "Sweet revenge."

Tony brushed his hands over Pepper's skin, which looked warm even from where Bruce was sitting. "Worth it. You look great."

While they kissed, Bruce poured himself more tea.

"Woah, slow down there, party animal." Tony said. He held the champagne aloft. "Dr. Cho's people called my people. We're celebrating."

Pepper clinked one of the glasses she was holding against the other two. "Well done."

Bruce tried to return her smile. "You two didn't fly all the way back here just to — " A glass was shoved in his face as Tony stood.

"That's exactly what we did," he said. "U-Gin is a huge get, and I'm all about the responsible fiscal expansion of our company today. Aren't I, honey?"

Pepper leaned around him. "I have a baby shower to attend tomorrow." Her tone was one of reassurance. "Tony's pouting."

"You want a baby shower, you say the word," Tony said, tipping the champagne bottle against Pepper's glass.

"Loud and clear," Pepper agreed, gazing back up at him. "When we're ready."

"Eighty-four percent?"

"Eighty-eight."

The grins in their voices were audible even as Bruce stared into his champagne. He wished they'd done the toast already, if only so he'd have something to do with his hands.

"To Bruce," Pepper cried, thrusting up her glass.

"To sealing the deal," Tony added with a lusty wink. "You're a bit out of practice, but I'm sure the good doctor was gentle."

"Ha, ha," Bruce allowed, clinking glasses and taking a long drink. There was a certain smug satisfaction to be had in a secret; Natasha had never been wrong about that.

After downing her glass, Pepper fumbled into Tony's inside jacket pocket and pulled out Bruce's tie. "We found this on the floor of your lab, and Tony's been cracking wise ever since."

Bruce took it back, stopping himself from tripping over an explanation. Nothing incriminating about a tie. Were Tony to rifle through his desk draws on the other hand — that would be the start of a long conversation and, depending on how it went, the end of an arrangement. Natasha wouldn't hesitate.

A very unladylike sound issued out of a very embarrassed Pepper. "Excuse me," she said under her hand, teetering further into the study.

Tony settled back on the plush sofa, calling after her, "Need me to hold your hair?"

"That will never be necessary," was her muffled but dignified reply.

Tony leaned toward Bruce to refill his glass. "Think I should warn her that Stark fetuses don't play fair?"

"I think she knows you well enough to have guessed that, Tony."

He smiled and gave Bruce's knee a couple pats. He plucked up the note, eyebrow perked. "Well, well. I knew you'd have Cho eating out of the palm of your hand. Koreans, culturally speaking, respond very well to humility. Don't ask how I learned that."

"I bet they'd respond even better to not being stereotyped."

"See, you're sensitive, too. Women love that," Tony said, irony thick. "But, really, how high did the sparks fly?"

Bruce was already shaking his head from the joke, now he did it in earnest. "Tony, no."

"Come on, Banner. She's yours to a capital T for type. And she already has the hots for your research. 'Consider me a partner," he quoted, emphasis salacious. "That's an invitation to, ah, collaborate if I've ever heard one. And I have."

"I'm not discussing this."

"Too late, mon ami. The seed has been planted. I already have your visits to Seoul on the docket. She doesn't like robots? I'll send her a man and tickets to the opera. Story writes itself."

Tony toasted. Bruce just drank.

"We have got to figure out what to do about Romanoff, though."

Bruce choked, but kept himself from coughing. "What? Why — uh, what do you mean?" Smooth.

"Dara's reports are incredibly comprehensive. Romanoff putting in an appearance at your lecture? Romanoff coming down to the gift shop to comp the tab and promise autographs? She's up to something."

Lots of things simultaneously, no doubt. An ego boost for him, and for her — "Maybe she just wanted to make a good impression." Nobody wanted to be the bad guy all the time. And, with SHIELD gone, she didn't have to be anymore. Bruce wondered if that had truly sunk in yet.

"Spycraft. She's collecting assets. She's got JARVIS running some Privacy Protocol, and he won't tell me anything about it. Unless you've remembered who your real friends are, buddy?"

"I assure you, sir, Ms. Romanoff's protocol is well within her rights as a resident."

Tony threw an incredulous look Bruce's way. "He doesn't even have bodily urges, and she's somehow got him defending her. How does she do it?"

"'Each of the residents of this Tower is afforded a full and complete level of privacy to be determined at their own discretion.' I am quoting Ms. Potts," JARVIS returned.

"And doing me justice, JARVIS." Pepper's posture was almost back to its usual level of discipline, and she came to stand over Tony with her hands on her hips. "What are these accusations? Are you bored?"

"She didn't even send me the complete mission specs; Hill forwarded them to me."

"Oh, well that seals it. You light the torches, I'll get the pitchforks." Bruce made sure it came out soft and wry, but there was an edge there. Anger on her behalf, maybe. Maybe chagrin at being the last one to speak up. He put the champagne aside and freshened up his tea.

Tony gestured around the room. "Assets and allies, this is what she does." He held out a hand for Pepper to help him up. "HYDRA survived underground. Why not SHIELD? Can you even picture Romanoff without an agenda?"

Something bitter and sweet wrenched up from Bruce's chest, spread over his lips. From behind his mug, he said, "Sounds like a fantasy."

"Thank you. All I'm saying."

"I have a fantasy," Pepper interjected.

Tony's attention turned on a dime. "Does it involve practice making a baby Potts-Stark?"

She cupped her hand to whisper into Tony's ear for a long moment.

"Geez, not in front of my folks." He turned Pepper toward the colossal portrait of Howard and Maria Stark hanging above the empty fireplace, then swooped her into his arms, bouncing her to make her squeak twice.

Pepper's fingers waggled at him over Tony's shoulder. "Remember to eat something before you go to bed."

Rounding the corner, Tony said, "Enjoy your bang up evening, Friar Tuck."

Bruce snorted. Tony had broken out that nickname the last time he'd pledged to get Bruce laid. Only this time, Bruce had a smug little secret and Tony couldn't tell the difference. Dramatic irony or proof that Bruce was a lost cause?

Or maybe the diffeƒrence was that Tony wasn't trying to get Bruce laid, he was trying to strongarm him into a happy ending. Like Howard Stark before him, when Tony had quit the playboy lifestyle, he'd struck a reservoir of traditional values. Tony wanted a wife and kids and a legacy worthy of passing down. These were sentiments that could fill a man with virtue and pride, Bruce remembered. They should have demanded caution, but more often inspired shortcuts.

So now he lived on borrowed pleasures. A stuffed leather chair, the best tea money could buy. Revolutionary tech and collaborators who saved the world. An arrangement with a whip-smart, unpredictable woman who'd seen something in him worth putting on her agenda. Less than he wanted, more than he deserved.

Natasha, she wanted less, deserved more. She couldn't see it, but maybe he could teach her to. The idea filled him with a guilty sort of anticipation. He could picture an ending for them now. He'd be a learning experience, a small but integral part of her future happiness, and — for all the mess they'd made of the past — they'd look back on each other in fondness.

Bruce chuckled, out loud and at himself. Optimism as a coping mechanism. Even at his age, he was still learning. There was wisdom in that, at the very least.

— • —


End file.
